1,5-Pentamethylene diisocyanate (PDI), and modified substance (e.g., a polyisocyanate composition such as isocyanurate) obtained by modifying 1,5-pentamethylene diisocyanate are used as a material of, for example, polyurethane resins.
1,5-Pentamethylene diisocyanate is produced, industrially, for example, by phosgenation of 1,5-pentamethylenediamine (PDA).
Furthermore, 1,5-pentamethylenediamine, i.e., a material of 1,5-pentamethylene diisocyanate, is gaining attention as a material of polymer derived from biomass, for example, as a material of polyurethane, a material of polyamide, etc.; and is produced, for example, by biochemical methods such as fermentation and enzymatic method.
As a method for producing 1,5-pentamethylenediamine, for example, a method in Patent Document 1 below is known: lysine decarboxylase acts on lysine as a substrate to be converted to 1,5-pentamethylenediamine (also called: 1,5-diaminopentane, cadaverine).
In the enzymatic decarboxylation of lysine, cells that express lysine decarboxylase may be used; however, it has been known that even if the cells that express lysine decarboxylase are not used in a larger amount, by giving treatments to these cells, compared with the case without treatment, reactivity per unit cell can be improved. The reactivity per unit cell indicates reaction yield and production rate per cell that expresses lysine decarboxylase. As such methods for treating cells, for example, the following methods have been proposed: a method in which cells are disrupted by ultrasonic treatment, using Dyno Mill, French Press, etc. (see Patent Document 1 below), or a method in which cells are treated with additives such as an organic solvent, a surfactant, etc. (see Patent Document 2 below).
Furthermore, for example, a method in which bacterial cells collected by centrifugal separation were frozen at −80° C., and thawed on ice when in use (see Patent Document 2 below) has been known.
As still another method that has been proposed is a method in which Escherichia coli in which lysine decarboxylase is localized on cell surface is used to improve reactivity (see Patent Document 1 below).
For example, Patent Document 1 below shows that when recombinant Escherichia coli in which lysine decarboxylase is expressed in the cells are collected from a culture solution and allowed to act on L-lysine hydrochloride without any treatment, the yield of 1,5-pentamethylenediamine was 15% with a reaction for 150 hours and the production rate was 0.001 mol/L·hr. On the other hand, it has been clarified that reactivity improves as follows: when using cell-disrupted solution subjected to ultrasonic treatment, the yield was 53% with a reaction for 10 hours, and the production rate was 0.072 mol/L·hr; and when Escherichia coli in which lysine decarboxylase was localized on cell surface was used, the yield was 90% with a reaction for 72 hours, and the production rate was 0.017 mol/L·hr.